Java Basics

Java, a versatile and powerful programming language, follows a structured syntax that requires a class and method declaration for code execution. Every Java program begins with the main() method, serving as the entry point for execution.

Example of Java Syntax:

public class HelloWorld {
public static void main(String[] args) {
System.out.println(“Hello, World!”);
}
}

In Java, variables act as placeholders for data, while data types specify the type of values that variables can hold. Type casting allows conversion between different data types.

Example of Variables and Type Casting:

int age = 25;
double height = 5.9;
char grade = ‘A’;

// Type Casting
int newAge = (int) height;

Java supports various operators like arithmetic, relational, logical, and bitwise, enabling developers to perform operations on variables and constants. Expressions combine variables and operators to yield results.

Example of Operators and Expressions:

int a = 10, b = 5;

int sum = a + b; product = a * b;
boolean isEqual = (a == b);
boolean isGreaterThan = (a > b);

Java offers control flow statements to execute code based on specific conditions. The if-else statement allows conditional execution, while the switch statement handles multiple possible outcomes based on the value of an expression.

Example of Control Flow:

int marks = 85;

if (marks >= 90) {
System.out.println(“Grade: A”);
} else if (marks >= 80) {
System.out.println(“Grade: B”);
} else {
System.out.println(“Grade: C”);
}

Loops enable repeated execution of code until a specified condition is met. Java provides three types of loops: for loop, while loop, and do-while loop, each serving different looping requirements.

Example of Loops:

// For Loop
for (int i = 1; i <= 5; i++) {
System.out.print(i + ” “);
}

// While Loop
int x = 1;
while (x <= 5) {
System.out.print(x + ” “);
x++;
}

// Do-While Loop
int y = 1;
do {
System.out.print(y + ” “);
y++;
} while (y <= 5);

Java’s robust exception handling mechanism allows developers to deal with unexpected errors and ensure graceful program execution. Exception handling includes try, catch, and finally blocks.

Example of Exception Handling:

try {
int result = 10 / 0; // ArithmeticException
} catch (ArithmeticException e) {
System.out.println(“Error: ” + e.getMessage());
} finally {
System.out.println(“Exception handling completed.”);
}